This is a randomized, prospective study whose primary goal is to determine the short-term effects of smoked marijuana on the pharmacokinetics of indinavir, the immune system, and the level of HIV-1 viral load. Subjects receive either marijuana cigarettes, dronabinol capsules, or placebo capsules. Subjects will be hospitalized because legal use of smoked marijuana is restricted to medically supervised settings. The inpatient setting also permits investigators to measure plasma THC levels as a means to assess the total dose delivered, and to rigorously assess the safety parameters and measures of possible efficacy including appetite, food intake, weight, and body composition.